A saddle-ridden type vehicle such as a motorcycle has an engine and a cooling device configured to cool the engine. When the engine is a water-cooling type engine, the saddle-ridden type vehicle is provided with a variety of components, as cooling system components configuring the cooling device, as follows.
That is, the saddle-ridden type vehicle is provided with a water pump configured to discharge cooling water, a water jacket configured to flow the cooling water around a cylinder and a cylinder head of the engine and to thereby cool the cylinder and the cylinder head, and a radiator configured to cool the cooling water, of which temperature has increased resulting from the cooling of the cylinder and the cylinder head, by traveling wind. In addition, the saddle-ridden type vehicle is provided with a thermostat configured to switch a circulation path of the cooling water, which is to be discharged from the water pump, to flow in the water jacket and then to return to the water pump without flowing in the radiator, and a circulation path of the cooling water, which is to be discharged from the water pump, to flow in the water jacket and the radiator and then to return to the water pump.
Also, in order to form the two circulation paths, a piping configured to supply the cooling water from the water pump to the water jacket is provided between a discharge port of the water pump and an inlet of the water jacket, a piping configured to deliver the cooling water from the water jacket to the radiator is provided between an outlet of the water jacket and an inlet of the radiator, and a piping configured to return the cooling water from the radiator to the water pump is provided between an outlet of the radiator and an intake port of the water pump. In addition, a bypass piping configured to return the cooling water from the water jacket to the water pump without flowing the cooling water in the radiator is provided between the outlet of the water jacket and the intake port of the water pump.
For example, in a motorcycle disclosed in Patent Document 1, the above-described cooling system components are disposed as follows. That is, when describing front, rear, right, left, upper and lower directions on the basis of a driver sitting on a seat of the motorcycle, the water pump is attached to a rear-lower part of a left side of the engine, as shown in FIGS. 2 to 5 of Patent Document 1. Also, the cooling water inlet of the water jacket is disposed at a front part of the engine, and the cooling water outlet is disposed at a rear part of the engine. Also, the radiator is disposed at the front of the engine, and the cooling water inlet of the radiator is disposed at a right part of the radiator and the cooling water outlet is disposed at a left part of the radiator. Also, the radiator adapted for the motorcycle is a so-called transverse flow type. The cooling water is enabled to flow in a right-left direction (in the example, from right to left) in the radiator and is thus cooled. Also, the thermostat is disposed at the rear part of the engine, and is directly connected to the cooling water outlet of the water jacket.
Also, in the motorcycle disclosed in Patent Document 1, the piping (cylinder inlet hose) configured to connect the discharge port of the water pump and the inlet of the water jacket extends over a range from the rear-lower part of the left side of the engine to the front part of the engine. Also, the piping (radiator inlet hose) configured to connect the thermostat directly connected to the outlet of the water jacket and the inlet of the radiator extends from the rear part of the engine toward the front of the engine through the right side of the engine. Also, the piping (radiator outlet hose) configured to connect the outlet of the radiator and the intake port of the water pump extends from the left part of the radiator toward the rear-lower part of the left side of the engine. Also, the left part of the radiator is formed with a separate inlet above the cooling water outlet, and the separate inlet is in communication with the outlet of the radiator without interposing a radiator core. Also, the bypass piping (bypass hose) is connected between the inlet and the thermostat directly connected to the outlet of the water jacket, and extends from the rear part of the engine toward the front of the engine through the left side of the engine.
Patent Document 1: Japanese Patent Application Publication No. 2007-85264A
In the saddle-ridden type vehicle of the related art, the pipings configured to connect the cooling system components such as the water pump, the water jacket, the radiator and the like may traverse laterally the engine. For example, in the motorcycle disclosed in Patent Document 1, the radiator inlet hose traverses a right side of the cylinder and the bypass hose traverses a left side of the cylinder head.
When it is intended to improve a design property of the saddle-ridden type vehicle, an outward appearance of the engine as seen from a side is important. When the piping traverses laterally the cylinder or cylinder head of the engine, the outward appearance of the engine as seen from a side is deteriorated, so that the design property of the saddle-ridden type vehicle may be lowered.
Also, in order to implement a lightsome handling property of the saddle-ridden type vehicle (mainly, a motorcycle), it is preferably to make a vehicle width of the saddle-ridden type vehicle small. However, when the piping is configured to traverse laterally the engine, it is difficult to make the vehicle width of the saddle-ridden type vehicle small.
Also, when the piping is configured to traverse laterally the engine, it is difficult for the traveling wind to collide with the engine, so that cooling performance of the engine may be lowered.
Also, when the piping is configured to traverse laterally the engine or when the pipings are dispersedly distributed at the right and left sides of the engine, it is difficult to secure a space in which other components relating to the engine are to be disposed.